The early diagnosis of disease can significantly impact the outcome for a patient as well as significantly reduce the costs of treatment and care. The diagnosis of diseases at the earliest stages requires ultra-sensitive, multiplex assays. The sensitivity of an assay is limited by the noise within the assay. In biological assays, noise tends to arise primarily from non-specific binding (NSB), wherein both non-targeted low-affinity molecules present at high abundance and the targeted molecules at low abundance bind to the background surface. This results in fluctuations in the background measurements thereby compromising the assay sensitivity. Within the prior art microarray assays and digital assays are two of the most promising technologies exploited today. Whilst antibody microarrays offer high density analysis with low sample volumes their sensitivity is inadequate for early detection. In contrast, whilst digital assays can reach single molecule resolution they completely lack, or have limited, multiplexing capabilities and hence are not easily scaled for large-scale protein analysis. However, irrespective of these tradeoffs, neither technology addresses NSB.
Accordingly, it would be beneficial to provide assays that simultaneously provide high assay sensitivity, multiplicity and noise rejection in a single platform.